POS1520-HPR RHEUMATOLOGY PATIENTS TREATED WITH A bDMARD PERSPECTIVE TOWARDS THERAPEUTIC DRUG MONITORING
Authors: M. Leeuw, S. Atiqi, F. De Vries, L. Boekel, F. Hooijberg, M. Nurmohamed, G. J. Wolbink, C. Krieckaert
Journal: Annals of the Rheumatic Diseases (2022)

Background Therapeutic Drug Monitoring (TDM) is a tool to determine the optimal dose of a drug for individual patients using measurement of blood concentrations and, optionally, anti-drug antibodies (ADA). In the field of rheumatology interest in applying TDM is increasing. A recent study by Syversen et al., the NOR-DRUM B trail, supports TDM as a treatment strategy. This study showed that treatment with proactive TDM was more effective then treatment without TDM. Applying TDM creates a more personalized treatment for individual patients, therefore it is relevant to understand the patients perspective towards TDM. Objectives To study the perspective of rheumatology patients treated with a bDMARD in a personalized fashion using TDM. Methods Adult rheumatology patients from the Amsterdam Rheumatology and immunology Center who participate in the COVID-19 prospective cohort study (Nederlands Trial Register, trial ID NL8513) received a digital questionnaire which comprised, in addition to demographic items, of three TDM topics: familiarity, attitude and risk assessment. Results Participants were selected based on the following criteria: treatment with a bDMARD and a fully completed questionnaire (n=888). Table 1 shows characteristics of study population. Table 1. Characteristics of study population Total N= 888 Age, yr Mean (SD) 55 (13) Gender, female - N (%) 575 (65) Diagnosis* - N (%) RA 511 (58) PSA 172 (19) AS 203 (23) Axial and peripheral SpA 21 (3) Other 17 (2) bDMARD** - N (%) Adalimumab 242 (27) Etanercept 352 (40) Other 297 (33) * Some patients reported more than one diagnosis ** Three patients reported more than one bDMARD Sixty-six percent (n=582) of the participants had never heard of the concept ‘personalized dosing, using TDM’. After explaining the concept 60% (n=535) of the participants answered they have a positive attitude towards the concept (Figure 1). Participants with a positive attitude received a follow-up question. They were asked which of the following related aspects: individual dosing, costs, safety and other, they thought was most relevant regarding the concept. Multiple answers were possible. Ninety-four percent (n=502) reported as the main reason for having a positive attitude, that the treatment can be personally adjusted. The second and third reasons, respectively, were safety 43% (n=230) and costs 27% (n=142) of the treatment. Figure 1. Attitude towards concept of TDM against being familiar with concept of TDM Five percent (n=43) of the participants had a negative attitude towards the concept. Main reasons were; previous experience with unsuccessful dose reduction and unwillingness to change current treatment due to the fact that several previous treatments were ineffective. Participants were also asked what amount of risk they are willing to take when presented with five different situations; worsening rheumatologically symptoms: e.g. pain and swelling, increased fatigability, necessary treatment with prednisone, switching to another bDMARD or more frequent visits to rheumatologist. Majority of the patients reported for each of the five situations, respectively: 37% (n=330), 40% (n=359), 51% (n=453), 48% (n= 426) and 29% (n=262) that they would only be willing to take a negligible risk, &lt; 0.1%. Conclusion Majority of participants was not familiar with the concept of personalized dosing using TDM. However, the majority had a positive attitude towards the concept. The main reason for a positive attitude is that the treatment can be personally adjusted. On the other hand, patients who are currently being treated with a bDMARD were only willing to take a negligible risk when it comes to their own treatment. References [1]Syversen, S. W., Jorgensen, K. K., Goll, G. L., Brun, M. K., Sandanger, O., Bjorlykke, K. H., Haavardsholm, E. A. (2021). Effect of Therapeutic Drug Monitoring vs Standard Therapy During Maintenance Infliximab Therapy on Disease Control in Patients With Immune-Mediated Inflammatory Diseases: A Randomized Clinical Trial. JAMA, 326 (23), 2375-2384. doi:10.1001/jama.2021.21316 Disclosure of Interests Maureen Leeuw: None declared, Sadaf Atiqi: None declared, Fenna de Vries: None declared, Laura Boekel: None declared, Femke Hooijberg: None declared, Michael Nurmohamed Speakers bureau: Abbvie, Jansen, Celgene, Consultant of: Abbvie, Grant/research support from: Abbvie, Amgen, Pfizer, Galapagos, BMS, Gert-Jan Wolbink: None declared, Charlotte Krieckaert: None declared